Technical SEO in plain words: speed, crawling and indexing
For owners who hear terms like Core Web Vitals and canonical tags and want to know what they mean. After reading, you can run the basic checks yourself and brief a developer on what to fix.
Technical SEO makes sure Google can reach, read and store your pages, and that people can use them quickly on a phone. Focus on four things: pages load fast and pass Core Web Vitals, nothing important is blocked from crawling, each page has one indexable address, and the site works well on mobile. Say a clinic's site takes 6 seconds to show its main image on mobile: getting that under 2.5 seconds meets Google's 'good' mark for that measure.
Speed is measured by three Core Web Vitals
Google measures page experience with three Core Web Vitals, based on data from real Chrome users. A page counts as 'good' when at least 75% of visits meet each mark.
You can see your scores for free in PageSpeed Insights and in the Core Web Vitals report in Search Console. Speed works more like a tiebreaker than a main ranking factor, but it has a large effect on whether visitors stay, book and buy.
- Largest Contentful Paint (LCP): how fast the main content, often the hero image, appears. Good is 2.5 seconds or less.
- Interaction to Next Paint (INP): how quickly the page responds when someone taps or clicks. Good is 200 milliseconds or less. INP replaced an older measure, First Input Delay, in March 2024.
- Cumulative Layout Shift (CLS): how much the page jumps around while loading. Good is 0.1 or less.
Most speed fixes are simple
Most slow small-business sites are slow for the same few reasons, and most of the fixes need no code.
- Resize and compress images before uploading, and use modern formats such as WebP where your platform supports them.
- Do not lazy-load the main image at the top of the page; lazy-load images further down instead.
- Remove apps, plugins and tracking scripts you no longer use. On Shopify, uninstalled apps can leave code behind in the theme.
- Limit custom fonts to two families and a few weights.
- Give images and embeds fixed sizes so the layout does not jump.
Crawling problems usually come from a few settings
If Google cannot crawl a page, nothing else matters. The usual causes are a robots.txt rule that blocks too much, a noindex tag left on after a redesign, links that only work with JavaScript, broken links that lead to 404 error pages, and chains of redirects where one old address forwards to another and then another.
Robots.txt also controls AI crawlers. GPTBot and OAI-SearchBot belong to OpenAI, ClaudeBot to Anthropic, PerplexityBot to Perplexity and CCBot to Common Crawl. Google-Extended controls whether Google may use your content for Gemini training; it does not affect Google Search. Block these only on purpose, because blocking a search bot can keep you out of that assistant's answers.
Indexing problems usually come from duplicates and thin pages
Google wants one address per page. The same page reached through http and https, with and without www, or with tracking codes added to the address looks like several pages. Redirect every version to one, and use a canonical tag to name the main address where duplicates are unavoidable.
Thin pages are the other common cause: empty category pages, tag archives and near-identical location pages. Improve them, merge them, or mark them noindex. Then use the Pages report in Search Console to confirm the pages you care about are indexed.
Google judges your site by its mobile version
Google now uses the mobile version of a site for indexing and ranking. If text, links or structured data appear on desktop but are hidden or missing on mobile, Google may not count them. Check your key pages on a real phone: text should be readable without zooming, buttons easy to tap, and pop-ups should not cover the content as soon as the page loads.
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Questions people ask
Do I need a perfect PageSpeed score?
No. The lab score is a guide. What counts is passing the three Core Web Vitals for real users, which Search Console shows.
What is a canonical tag?
A line of code that tells Google which address is the main version of a page when several addresses show the same content.
Should I block AI crawlers?
Only if you have a clear reason. Blocking search-focused bots such as OAI-SearchBot or PerplexityBot can keep you out of those assistants' answers, while blocking training-only controls such as Google-Extended does not affect Google Search.